for $a in doc("sortie-treetagger-3232.xml")//item
for $b in $a//element
let $sibling := $b/following-sibling::element[1]
where $b/a[4] = "ADJ" and $sibling/a[4] = "NOUN"
return <ADJ-NOM>{$b/a[2]/text(), ' ', $sibling/a[2]/text()}</ADJ-NOM>